JPH0222142B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a groove-type induction furnace type hot-dip galvanizing furnace which basically consists of a hot-dip galvanizing bath in which material is immersed and an inductor for induction heating provided on the side wall of the vessel.

In the hot-dip galvanizing method using a channel-type induction furnace type hot-dip galvanizing furnace, a zinc alloy is formed on the surface of the iron-based alloy by immersing it in a zinc bath.This creates a highly corrosion-resistant surface metal, so it can be used in all weather conditions. This method is widely used in the industrial world, mainly for buildings exposed to high temperatures. However, when the above-mentioned channel induction furnace hot-dip galvanizing furnace is used, dross is generated at the bottom of the bathtub.

This dross is a result of a zinc-iron compound produced by a reaction when ferrous materials are immersed, which flows into the bath and settles at the bottom of the furnace due to the difference in the specific gravity of the zinc bath and this compound. be. The above zinc-iron compound is originally in a solid phase at the operating temperature of the zinc bath, and these fine crystals are deposited to form dross, but they cannot be completely separated and are dissolved in the liquid phase of zinc. This emulsion-like material as a whole is called dross because it is in the form of an emulsion in which solid crystals are dispersed and can be distinguished as having a significantly higher viscosity than molten zinc. This dross is unsuitable as a plating bath material due to its high viscosity, and if a portion of this dross adheres to the plating material, the surface will be uneven and the product will be considered defective.
Therefore, the generation of this dross is considered to be a necessary evil in the hot-dip galvanizing process, and although various methods for reducing the amount of dross generated have been studied, no effective means have yet been discovered. Therefore, on the spot,
When a certain amount of dross accumulates, a crab bucket or the like is placed in the bath to pull up the dross, and the dross is removed from the bath.The dross is cooled and solidified, and sent to a known zinc distillation process to regenerate pure zinc. This method is used. However, this regeneration costs a lot of money, so in the hot-dip galvanizing method, reducing the amount of dross/product throughput has become a major issue in order to improve the economic efficiency of the process.

Therefore, the object of the present invention is to provide a groove-type induction furnace hot-dip galvanizing furnace with a device that reduces the amount of dross accumulated as a whole by reducing the zinc content in the dross generated.

Although the mechanism of the generation of dross described above has not been clarified at present, it has been confirmed through experiments that the zinc content of dross generated in the presence of fluidity is lower than that of dross generated in the absence of fluidity. It is known that the zinc content of Based on this fact, the following hypothesis seems to hold, which will be explained below. The generated solid crystals of the zinc-iron compound emerge into the bath and settle downward, but during this settling, the liquid zinc adhering to the surroundings of the crystals is mixed with the dross already present. Connect and unify. If at this time some kind of flow occurs in the zinc solution other than the natural sedimentation rate, the liquid zinc adhering to the crystal grains will be torn off due to the flow, reducing the amount of zinc that already exists. Becomes one with the dross body. Furthermore, the crystal grains adhering to the dross release part of the zinc into the flow due to the flow. The above statement of dross formation in the presence of natural sedimentation and forced flow is one hypothesis, as mentioned above, but the zinc content of dross generated in the presence of fluidity is lower than that in the absence of fluidity. This idea is based on the fact that the zinc content is lower than the zinc content of dross generated in the state.

Therefore, in the present invention, based on the above facts, a mechanism for causing a forced flow in the bathtub of a groove type induction furnace hot dip galvanizing furnace is provided.

Examples of the above mechanism will be described in detail below.

The drawing shows a state in which a plating material 3 is put into a groove-type induction furnace type hot-dip galvanizing furnace according to the present invention, which basically consists of a molten zinc bath 1 and an induction heating inductor 2, and plating is being performed. In the vicinity of the inductor 2 of the bathtub 1, two vertical partition plates 4 and 5 made of fire-resistant material are installed so that the upper end level of the partition plates is lower than the level of the molten zinc. A flow path 6 for molten zinc exists in the upper part of the plate 5, and it is supported by a support 8, and the partition plate 4, which is located at the lower level of the two partition plates 4 and 5, is made vertically movable by this support 8. , so that the molten zinc flow path 7 below the diaphragm plate 4 can be adjusted. In the figure, the plating material 3 is plated in the bath 1 of the hot-dip galvanizing furnace, and a dross body 9 and a zinc-iron compound 10 are produced.

In the above configuration, the high temperature molten zinc heated by the inductor 2 passes through the partition plate 4, as shown by arrow a.
5 to the plating material 3 through the flow path 6 above;
Due to the absorption of heat by the material, the temperature decreases, the specific gravity increases, and it descends as shown by arrow b. At this time, a zinc-iron compound 10 is produced by the reaction with the plating material 3, and the zinc-iron compound 10 passes through the flow path 7 below the partition plate 4 as shown by arrow C. Here, the zinc-iron compound 10 is deposited on the dross body 9 formed at the bottom of the furnace. Here, the diaphragm plate 4 is pulled up according to the accumulated amount of the dross 9, so that the increasing dross 9 is always swept away by the flow of molten zinc.

Although two partition plates were used in the above embodiment, three or more partition plates may be used if necessary. In this case, the partition plates below the topmost partition plate may be movable up and down.

As described above, according to the present invention, the amount of zinc in the generated dross can be reduced by forcibly causing a flow of molten zinc into the bath of a channel induction furnace type hot-dip galvanizing furnace. As a result, the amount of dross generated during the plating process can be reduced.
The amount of dross/product throughput can be reduced, the number of dross removal operations can be reduced, and the economic efficiency of the plating process can be improved.

[Brief explanation of drawings]

The drawing is a front cross-sectional view when the trench type induction furnace type hot-dip galvanizing according to the present invention is being performed. 1... Bathtub, 2... Inductor, 4, 5...
Shikiri board, 8... support tool.

Claims (1)

[Claims] 1 In a groove-type induction furnace hot-dip galvanizing furnace that basically consists of a molten zinc bath in which the material is immersed and an induction heating inductor installed on the side wall of the container, a fire-resistant material is placed near the inductor in the bathtub. Two or more vertical partition plates are provided, and the uppermost partition plate is fixed and supported with its upper end level lower than the level of the molten zinc, and the uppermost partition plate is fixed and supported at a level lower than the lower end of the uppermost partition plate. A groove-type induction furnace type hot-dip galvanizing furnace, characterized in that the groove-type induction furnace type hot-dip galvanizing furnace is equipped with a support that supports at least the lowest partition plate so as to be movable up and down.